Soil organic carbon stock in Abune Yosef afroalpine and sub-afroalpine vegetation, northern Ethiopia

Abstract

Introduction: Soil is the major reservoir of organic carbon. There is a paucity of soil organic carbon (SOC) stock data of afroalpine and sub-afroalpine vegetation in Ethiopia. Hence, this study was conducted to estimate the SOC stock and correlate it with soil physicochemical properties in Abune Yosef afroalpine and sub-afroalpine vegetation. Systematic sampling was employed to collect soil samples from upper 30 cm. Dry bulk density soil pH (1:2.5 water); organic carbon (Walkley and Black), and total nitrogen (Kjeldahl) were the methods used for soil analysis. Pearson correlation and linear regression analysis were performed in SPSS 24 statistical software. Results: The SOC stock of the study area was found to be 79.57 t C ha−1. Soil organic carbon stock showed statistically significant positive correlation with vegetation type (r = 0.522, p < 0.01), bulk density (r = 0.62, p < 0.01), total nitrogen (r = 0.41, p < 0.01), and altitude (r = 0.468, p < 0.01) and negative correlation with slope (r = − 0.298, p < 0.05). The present study revealed similar soil organic carbon stock (SOCS) with the Intergovernmental Panel on Climate Change (IPCC) default estimate for similar regions. Positive correlation of SOCS and altitude could be resulted from the variations in anthropogenic disturbances, temperature, and precipitation vegetation types. The negative correlation between SOCS and slope is the result from the predictably higher soil erosion at steeper slopes. Temporal livestock trampling increased the bulk density but never affected the SOCS to decline. Aspect did not show any significant relationship with SOCS due to either the under surveying of all aspects or similar solar radiation found in the study area. Moreover, gazing, aspect, and soil pH did not show statistically significant impact on SOCS. Conclusion: The SOCS of Abune Yosef afroalpine and sub-afroalpine vegetation is similar to the IPCC default estimate for similar regions. This is a great contribution both to the global and local terrestrial carbon sink.